Conventionally, avionics, engineers and certification bodies are improving and providing pilots and flight crews with information necessary to identify in-flight traffic. An approach has been to provide the flight crew with information on the location of other aircraft in the area. One exemplary system which is capable of providing this information, is known as a traffic alert and collision avoidance system (TCAS). The systems are required for all airliners flying the United States air space today. TCAS devices have been designed to interrogate transponders of other aircrafts, sometimes referred to as intruder aircraft. The TCAS system evaluates the threat of collision with other aircraft and coordinates an avoidance maneuver for the aircraft.
Recently, the aviation industry has worked to define a new standard of performance for Mode S transponders which are the communication devices used in most TCAS systems. The extension of the function of Mode S transponders is to provide more information about the state and plans of aircraft which are under surveillance. This extended information may collectively be called “enhanced surveillance”. The feature is designed to provide ground-based aircraft control and additional information to enable improved management of air traffic. Although this information is provided from Mode S transponders to ground-based air traffic control, it may be desirable and useful for a first aircraft to be able to interrogate a Mode S transponder and receive enhanced surveillance information from a Mode S transponder on a second aircraft.
Accordingly, there is a need for a system and method in which the first aircraft may request and receive enhanced surveillance information from other airborne Mode S transponders. Further, there is a need for a system and method in which the first aircraft may request and receive enhanced surveillance information from a second aircraft Mode S transponder and provide integrity checking of the position of the aircraft. Further still, there is a need for a airborne system onboard a first aircraft which may interrogate a second aircraft's Mode S transponder at a variable rate, the rate dependent upon the determined dynamics of particular requested data.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.